SOLID & HAZARDOUS WASTE
MANAGEMENT
Dr. Indrani Ghosh
Environmental Science, Adamas University
Solid and hazardous waste
• Solid waste is that material which arises from various human and animal
activities and which is normally discarded as useless or unwanted.
• Hazardous waste is any discarded material, liquid or solid, that contains
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substances known to be
(1) fatal to humans or laboratory animals in low doses;
(2) toxic, carcinogenic, mutagenic or teratogenic to humans or other lifeforms;
(3) ignitable with a flash point less than 600C;
(4) corrosive; or explosive or highly reactive
Common hazardous wastes
1. Cyanide and fluoride waste
2. Metal finishing waste
3. Sludge containing spent chemicals and water soluble
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chromium, lead
Mercury bearing waste
Pigment waste
Dye waste
Oily waste
Phenolic waste
Acidic sludge containing heavy metals
Rejected nickel catalyst containing oil
Waste disposal methods
1. Open dumping : dumping is open throwing of refuse so as to fill up lowlying areas. Open unregulated dumps are still the predominant method of
waste disposal in most developing countries. Most developed countries forbid
open dumping at least in metropolitan areas but illegal dumping is still a
problem
Advantages of open dumping :
➢ Reclamation of low lying or sloping areas
➢ Easy method of disposal, no planning required
➢ Transporting is the only cost
➢ By bacterial action the volume of refuse decreases and gradually converted
into humus that can be used in the agricultural land.
Waste disposal methods
Disadvantages of open dumping
▪ The refuse dump helps in mosquito and fly breeding
▪ The refuse dumps also serve as a source of food for rodents which spread diseases
like plague, salmonellosis etc.
▪ Bad smell and unpleasant appearance
▪ The loose refuse is dispersed by the action of the wind causing spreading of pollution
▪ Chemicals and other contaminants found in solid waste can seep into our
groundwater and can also be carried by rainwater to rivers and lakes that provide
essential wildlife habitat. These contaminates can also end up in our ground water,
rivers and lakes that are our sources for drinking water.
▪ Ocean dumping is nearly uncontrollable. Every year, nearly 25000 metric tons of
packaging, including bottles, cans and plastic containers are dumped at sea.
Waste disposal methods
2.Sanitary landfills: The modified and improved form of open dumping is
termed as “Sanitary Landfill”.
American Society of Civil Engineers (ASCE) defines sanitary landfill as “A
method of disposing off the refuse, on land without creating nuisances or
hazards to public health or safety by utilizing the principles of engineering to
confine the refuse to the smallest practical volume and to cover it with a layer
of earth at the conclusion of each day’s operation or at such more frequent
intervals as may be necessary”.
Advantages of Sanitary Landfill
The initial capital investment is low
Operational cost is moderate
Waste disposal methods
• Simple effective and cheap method
• A sanitary landfill is complete or final disposal method. It does not yield
residue or by-products which require further disposal like incineration or
composting
• It converts low-lying marshy wasteland or waterlogged area into useful area
(like parking lots, play ground etc.)
Disadvantages of Sanitary Landfill
✓ a large area is required
✓ Transportation cost is high
✓ Possibility of fire hazard due to formation of methane in wet weather
✓ Covering earth (selected soil) is required for top layer may sometimes be
difficult to obtain
✓ Since the dumped garbage may contain harmful and sometimes carcinogenic
non-biodegradable substances, the “leachate” may contaminate ground and
surface water
Waste disposal methods
3. Incineration: It is a controlled combustion process for burning
solid and wet waste and reduces them primarily to carbon dioxide
and other gases, water vapour, non combustible inoffensive soild
residue. High temperature in the range of 1540-17600C is
maintained to achieve complete combustion including bulky
items such as, metals, glass etc.
Waste disposal methods
Advantages of Incineration
✓ It requires less space than required for other methods
✓ Volume of garbage/waste is reduced by 75-80%
✓ This is the most effective sanitary method of refuse disposal and ensure complete
destruction of pathogenic bacteria, insects etc.
✓ Cost of transportation is not so high as incinerators are located within city limits
✓ Another term commonly used for this technology is energy recovery to waste to
energy because the heat derived from incinerated refuse is a useful resource.
Burning of garbage can produce steam used directly for heating buildings or
generating electricity.
✓ Adverse weather condition has no effect on the incinerator’s operation
Waste disposal methods
Disadvantages/Negative consequences of incineration
• The residual ash usually contains a variety of toxic components that make it
an environmental hazard. The EPA has found alarmingly high levels of
dioxins, furans, lead and cadmium in incinerator ash. One way to reduce
these dangerous emissions is to remove batteries containing heavy metals
and plastics containing chlorine before wastes are burned.
• The cost-effectiveness of garbage incinerators is the subject of debates.
Initial construction costs are high usually between $100 and $300 million for
a typical municipal incinerator
• Skilled personnel is required to operate the plant
3R in Waste Management
Recycling
• Recycling is the reprocessing of discarded materials into new, useful products.
• Some recycling processes reuse materials for the same purposes: for instance old
aluminum cans and glass bottles are usually melted and recast into new cans and
bottles.
• Other recycling processes turn old materials into entirely new products. Old tires,
are shredded and turned into rubberized road surfacing.
Benefits of recycling
➢ Recycling is usually a better alternative to either dumping or burning wastes.
➢ It saves money. Curbside pickup of recyclables cost around $35 per ton as
opposed to $80 paid to dispose of them at an average metropolitan landfill.
➢ Recycling drastically reduces pressure on landfills and incinerators. This helps in
reducing water and land pollution as landfills are a major source in contributing to
destruction of natural environment. Japan probably have the most successful
recycling programme in the world. Half of all household and commercial wastes
in Japan are recycled while the rest are about equally incinerated or landfilled.
Benefits of recycling
• Recycling lowers demands for raw resources. While many trees are cut down
continually, recycled paper made from certain trees is re-used repeatedly to
minimize felling/ deforestation. With re-cycled paper as an outstanding example,
a number of other natural resources can be reused this way.
• Reduces Energy Consumption: A large amount of energy is consumed by
processing raw materials at the time of manufacture. Recycling helps to
minimize energy consumption, which is crucial for massive production, such
mining or refining. This also makes the production process very cost-effective
and beneficial for manufacturers.
• Example : recycling of plastic bottles could save 50-60% of energy needed to
make new ones. Producing aluminum from scrap instead of bauxite ore cuts
energy use by 95%.
• Reduces Pollution: Industrial waste today is the main source of all types
of pollution. Recycling of industrial products such as cans, chemical, plastics
helps to cut down pollution levels considerably, as these materials are re-used,
instead of throwing them away irresponsibly.
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Drawbacks of recycling
• Not always Cost Effective: Recycling is not always cost-effective.
Sometimes, there may be a need to establish separate factories to process
reusable products. This may create more pollution as they would go under
the process of cleaning, storage and transportation.
• Recycled Products May not Last for Long: Recycled products are always not
of durable quality. Such items are mostly made of trashed waste, picked up
from heaps other waste products which are of fragile or overly used. For
this reason, recycled products are cheap and last for a shorter period.
• Unsafe and Unhygienic Recycling Sites: Recycling sites are often unsafe and
unhygienic. Places where all sorts of waste is dumped are conducive for
debris formation and spread of disease and other dangers caused by harmful
chemicals and waste. This not only causes widespread pollution but is
harmful for dedicated people who recycle such products. Such waste if
mixed with water, leads to leachate formation and leads to toxification of
water bodies including drinking water.
Composting
• Composting is a natural biological process, carried out under controlled
aerobic conditions (requires oxygen). In this process, various
microorganisms, including bacteria and fungi, break down organic matter
into simpler substances. The effectiveness of the composting process is
dependent upon the environmental conditions present within the composting
system i.e. oxygen, temperature, moisture, material disturbance, organic
matter and the size and activity of microbial populations.
• The organic compost resulting from this process makes a nutrient-rich soil
amendment that aids water retention, slows soil erosion and improves crops
yield.
Ways to reducing waste
1.
Buy foods that come with less packaging: shop at farmer’s markets or coops, using your own containers
2.
Take your own washable, refillable beverage container to meetings or
convenience stores
3.
When you have a choice at the grocery store among plastic, glass or metal
containers for the same food, buy the reusable or easier to recycle glass or
metal
4.
Separate your cans, bottles, papers and plastics for recycling
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Wash and reuse bottles, aluminum foil, plastic bags and so on for your
personal use.
6.
Compost yard and garden wastes, leaves and grass clippings
Hazardous waste management
1.Produce less waste
• The safest and least expensive way to avoid hazardous waste problems is to
avoid creating the wastes in the first place.
• Manufacturing process can be modified to reduce or eliminate waste production.
• Recycling and reusing materials also eliminates hazardous wastes. Many waste
products of one industry are valuable commodities in another
2. Convert to less hazardous substances
Physical treatments tie up or isolate substances.
• Charcoal or resin filters absorb toxins. Precipitation and immobilization in
ceramics or glass or cement isolate toxins from the environment. Plants, bacteria
and fungi can also detoxify contaminants.
• Incineration of waste above 10000C for a sufficient period of time causes
complete destruction.
• Chemical processing, such as, neutralization, removal of metals or halogens and
oxidation, can transform materials to nontoxic form
Hazardous waste management
• Secure landfills is one of the most popular solutions for hazardous waste
disposal.
• The first line of defense in a secure landfill is a thick bottom cushion of
compacted clay that surrounds a pit like a bathtub. Moist clay is flexible and
resists cracking if the ground shifts. It is impermeable to groundwater and
will safely contain wastes.
• A layer of gravel is spread over the clay liner and perforated drainpipes are
laid in a grid to collect any seepage that escapes from the stored material.
• A thick high density polyethylene (HDPE) liner protected from punctures
from soft materials covers the gravel bed. A layer of soil or absorbent sand
cushions the inner liner and the wastes are packed in drums, which then are
placed into the pit, separated into small units by thick berms of soil or
packing material.
• When the landfill has reached its maximum capacity, a cover much like the
bottom sandwich of clay, plastic and soil in that order-caps the site.
Vegetation stabilizes the surface and improve appearances.
Secure landfill